As described in Patent Document 1, a vehicle such as an automobile includes a warning device for generating a warning for the driver of the vehicle based on approach information about a moving object approaching the vehicle. Based on whether there is such a moving object and the distance and relative speed between the moving object and the vehicle, the warning device determines a collision prediction time, which is the time predicted to elapse before the moving object hits the vehicle. If the collision prediction time is less than a threshold value, the warning device generates a warning for the driver of the vehicle by illuminating a warning lamp or generating a warning sound. By warning the driver based on the collision prediction time in the above-described manner, the warning device generates a warning appropriately in accordance with the distance and relative speed between the vehicle and the moving object when the vehicle travels on the road.